Motor saw

ABSTRACT

In order to create ( 100 ) with a motor ( 101 ) which is fixed to a casing ( 102 ) and which shows an intake port ( 11 ) which is connected with a carbureter ( 16 ) for decoupling oscillations over an elastic suction hose ( 15 ), the carbureter ( 16 ) itself taking its bearing on the casing ( 102 ) by means of fixing means ( 21, 15 ), which avoids the disadvantages of the solution existing up to now and which makes possible especially a vibration-free bearing of the carbureter which is simple, easy servicing and which can be realized at low cost, it is proposed that the bearing of the carbureter ( 16 ) on the casing ( 102 ) is carried out substantially resiliently for damping or reducing the oscillations and the bearing of the resiliently hinged carbureter is carried out by means of an one-point suspension.

FIELD OF THE INVENTION

This invention relates to a motor saw with a motor which is fixed to acasing and which shows an intake port which is connected for decouplingoscillations with a carbureter over a resilient suction hose, thecarbureter itself taking its bearing on the casing by means of fixingmeans.

BACKGROUND OF THE INVENTION

Such a motor saw is known for example from the document DE-A1-42 34 483.

The carbureter of a motor saw driven by an internal combustion engine(generally a high-speed two-cycle engine) has a considerable influenceonto the operating behaviour of the device. Oscillations which come fromthe moving piston of the motor and act onto the carbureter can result inan irregular fuel supply which endangers a troublefree motor operation.For this reason, it is already known by the prior art for motors whichare provided with a carbureter to connect the carbureter with the motorby means of a resilient admission pipe and to additionally create aresilient suspension of the carbureter in the casing. Such resilientsuspensions can be made available by a few types of resilient elements,normally made of rubber. Due to such elements, it is possible to obtainan efficient vibration insulation of the carbureter. However, it is adisadvantage of such a suspension that sufficiently resilient elementsfor the vibration insulation make too important movements of thecarbureter possible. A resilient admission pipe is, for example, knownfrom DE-GM 1 762 310 or by SE-PS 8 6022 481-7. Because of thepermanently increasing requirements with respect to the reduction ofexhaust emissions, a safe motor operation is necessary. An exactadjustment of the carbureter is the condition of low exhaust emissions.Therefore, an oscillation reduced fixation of the carbureter in thesuction space would be very advantageous. Furthermore, the fixation ofthe carbureter should be simple and easy servicing at low cost. From theabove mentioned document DE-A1 42 34 483, it is now known to decouplethe oscillations from the intake port of the motor by a gas admissionpipe made of an elastomer. The carbureter is hinged to the operatingarea of the saw over a hinge joint in order to be able to moverelatively freely in direction of the gas admission pipe.

However, the known hinge joint has different disadvantages. On the onehand, such a connection is comparatively expensive and has acomparatively complicated structure because parts with hinge bores mustbe produced and the hinge joints must be equipped with correspondinghinge bolts. On the other hand, the mounting and dismounting forservicing is complicated because the hinge bolts must be mounted andlocked in the hinge joints with much expenditure and/or unlocked anddismounted. Finally, the hinge joint allows only a limited movability ofthe carbureter, namely in direction transversely to the hinge joint. Onthe contrary, a movability in direction of the hinge joint can only berealized with much expenditure if the hinge pins are configuredresiliently.

Therefore, it has also already been proposed with DE 197 53 689 A1 asuspension for a carbureter which comprises at least one resilientelement which is fixed to the casing and which is connected with thecarbureter in order to allow a certain extent of movement of thecarbureter relative to the housing, a supporting device limiting theextent of the movement. However, this is bound to disadvantages since,due to the limiting and the thus direct connected support of thecarbureter, vibrations are still transmitted in an extent which is notto be tolerated.

SUMMARY OF THE INVENTION

Therefore, the aim of the invention is to create a motor saw whichavoids the disadvantages of the solution until now and which especiallymakes possible a vibration free bearing of the carbureter which issimple, easy servicing and which can be realized at low cost.

This aim is achieved for a motor saw of the above mentioned type by thecharacteristics indicated in claim 1. Due to the renunciation accordingto the invention to a hinge joint of the carbureter on the casing bymeans of hinge bolts and the like and to any supporting and delimitingdevice, the bearing is much simplified. Simultaneously, due to theresiliently articulated one-point suspension, a bearing is obtainedwhich fixes the carbureter in space but which simultaneously decouplesit from the oscillations of the motor and of the casing due to theresilient movability in different directions in space. Due to therenunciation to supporting walls and stoppers, an efficient dampingdevice is created. Due to the preferably progressive characteristiccurve of the spring constant of the resilient element, it is obtainedthat higher frequency oscillations as well as oscillations with lowerfrequency are efficiently damped.

Due to the central arrangement of the damping part and to the chosenone-point fixing, a damping in all planes, i.e. in all directions isachieved.

A first preferred embodiment of the motor saw according to the inventionis characterized in that a seat made of an elastic material, especiallya resilient bushing made of rubber, is fixed to the casing and that thecarbureter is detachably snapped-in with a snap-in part into the seat orthe resilient sleeve. The carbureter can thus be very easily mounted bysnapping-in into the seat and dismounted by snapping-out of the seat.

A particularly simple snap-in procedure and a very movable bearingresult when, according to a preferred further development of theembodiment, the snap-in part is configured as a ball head. Due to therenounciation to snap-in edges, the snap-in part can be snapped in andout with a comparatively low resistance. The ball head acts additonallyas a ball joint.

A trunnion which is stuck through the sleeve (not represented) can alsobe configured instead of the ball head. Thus, the sleeve can beconfigured with still bigger dimensions (for example air chamber) inorder to achieve a special damping characteristic and to simultaneouslyguarantee a “fixed” adjustment (fixing).

A further embodiment of the resilient sleeve allows a configuration ofthe damping element which is much more resilient. Due to the veryresilient configuration, the mounting procedure of the damping elementnot together with the suction flange is possible. Therefore, the dampingelement is separated from the suction flange and preliminarly placed inthe mounting sequence. The suction flange is snapped-in later. For theconfiguration of the damping element, due to the ellispoidal form a very“smooth” characteristic curve in direction of the carbureter bottom canbe obtained. On the contrary, in the crankshaft axle direction, thespring characteristic will turn out harder. Thus, the whole suctionsystem can be positioned very smoothly but still axially safe.

Further embodiments result from the depending claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be explained in more detail below withreference to the attached drawings.

FIG. 1 shows in a sectional view a part of a preferred embodiment of amotor saw according to the invention with the motor and with thecarbureter connected therewith which is resiliently positioned in aresilient seat in the casing bottom over a ball head moulded on theintake manifold.

FIG. 2 shows a resilient sleeve in a schematical view.

FIG. 3 shows a schematical view of a further embodiment of a resilientsleeve in the mounting situation snapped-in the intake manifold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The motor 101 of a motor saw 100 is represented in FIG. 1 in a cutpartial view. The motor 101, which comprises a cylinder 10 with anintake port 11 and a discharge channel 12 as well as a piston 14, isscrewed with its crankcase 13 on the bottom 20 of a casing 102. Thecasing 102 encompasses the motor 101 at least partially and is connectedon top by a cap 24. Inside the casing 102, a suction space 19 which isbesides the motor 101 is separated by a vertical partition 23, wherebythis suction space is closed on top by a (removable) cover 22 and inwhich a carbureter 16, especially in form of a diaphragm carbureter, isplaced. The carbureter 16 is connected on the outlet side by a resilientsuction hose 15 to the intake port 11 of the motor 101. The suction hose15 penetrates through an opening in the partition 23 and is positionedthere in snap-in position. On the inlet side, the carbureter 16 changesinto an intake manifold 17 which is bent-off upwards and discharges intoan air filter 18.

A ball head 25 is moulded on the intake port 17 on the lower side, ballhead which snaps in into a resilient sleeve 21 of rubber. The resilientsleeve 21 possesses itself noses or trunnions with which it can bestuck-in in a snap-in position into one (or several) opening(s) whichare in the bottom 20 or with which it can be stuck through. Adifferently formed nose or a trunnion with undercut can be naturallyused instead of the ball head 25, whereby they can be stuck-in or stuckthrough into a correspondingly formed opening in the resilient sleeve orin a comparable resilient seat. However, the ball head 25 has theparticular advantage that it can be particularly easily stuck-in andthat it simultaneously acts as a ball joint.

Because of the resilient embodiment of the sleeve 21 or of the seat, thetransmission of oscillations to the carbureter 16 can be considerablyreduced. Simultaneously, the carbureter 16 which is connected (for thefurther avoiding of heat transmission and oscillations) over theresilient suction hose 15 with the cylinder 10 is fixed in all necessarydirections.

The mounting and dismounting are strongly simplified because of thesimple snapping-in of the ball head 25 into the opening provided forthis purpose in the resilient sleeve 21. For the mounting, first theresilient sleeve (seat) 21 is mounted in the bottom 20 of the casing102, then the intake manifold 17 with the carbureter suspended on it.The dismounting is carried out in the reverse order. No tool is requiredfor this.

In FIG. 2, a further embodiment of a resilient sleeve 26 is representedwhich consists of a resilient ring-shaped damping body 27 with fixingmeans 28, 29 moulded thereon for fixing on the casing bottom 20 and onthe intake manifold 17. The damping body 27 is optimally adjustable withrespect to the desired elasticity and damping behaviour through theselection of the diameter of the ring 27 a and of the cross-section ofthe body. The fixing parts 28, 29 can have different configurations. Thefixing part 28 shows a rod-shaped retaining arm 30 with an end-sidedsnap-in knob 31, while the fixing part 29 shows a rod-shaped retainingarm 32 with a snap-in connection 33. The snap-in knob 31 is pushed-ininto a correspondingly formed snap-in seat 34 on the intake manifold 17,while the retaining arm 32 is snapped-in into a corresponding seat (notrepresented) in the casing bottom 20.

A further embodiment of a sleeve 26 is represented in FIG. 3, theretaining arm 34 of which is stuck-in with the projecting end part 35into the casing bottom 20.

On the whole, it results from the invention a motor saw with an internalcombustion engine for which the carbureter is practically decoupled ofharmful oscillations in a simple, low-cost ways easy for mounting andservicing.

What is claimed is:
 1. A motor saw (100) with a motor (101) which isfixed to a casing (102) and which shows an intake port (11) which isconnected for decoupling oscillations with a carbureter (16) over aresilient suction hose (15), the carbureter itself taking its bearing onthe casing (102) by means of fixing means (21,25), characterized in thatthe bearing of the carbureter (16) on the casing (102) is carried outsubstantially resiliently for damping or reducing the oscillations andthe bearing of the resiliently hinged carbureter (16) is carried out bymeans of a one-point suspension, said one-point suspension comprising anelastic, removable attachment between a lower portion of an intakemanifold (17) an the casing (102).
 2. A motor saw according to claim 1,characterized in that a seat made of an elastic material, is fixed tothe casing (102) and that the carbureter (16) is detachably snapped-inwith a snap-in part (25) into the seat.
 3. A motor saw according toclaim 1, characterized in that the one-point suspension is substantiallyresilient for damping having a spring characteristic configured fordamping both higher frequency oscillations and lower frequencyoscillations.
 4. A motor saw according to claim 2, characterized in thatthe snap-in part (25) is configured as a ball head.
 5. A motor sawaccording to claim 2, characterized in that the casing (102) comprises abottom (20) and that the seat is snapped-in into an opening in thebottom (20) provided for this.
 6. A motor saw according to claim 5,characterized in that the casing (102) comprises a partition (23) placedsubstantially vertically to the bottom (20) between the motor (101) andthe carbureter (16) and that the resilient suction hose (15) extendsthrough an opening in the partition (23) and is positionable in asnap-in position in said opening.
 7. A motor saw according to claim 2,characterized in that the carbureter (16) is removably attached tointake manifold (17), said intake manifold (17) comprising the snap-inpart (25) moulded thereon.
 8. A motor saw according to claim 1,characterized in that the means of an one-point suspension, furthercomprises a first fixing means (28) for the removable fixing to thecarbureter (16) and a second fixing means (29) for the removable fixingto the casing (102) and a resilient connecting means (27) between thefirst fixing means (28) and the second fixing means (29).
 9. A motor sawaccording to claim 8, characterized in that the resilient connectingmeans (27) is configured ring-shaped.
 10. A motor saw according to claim8, characterized in that the first fixing means (28) is configuredT-shaped and can be pushed-in into a corresponding T-shaped receivinggroove or recess on the carbureter (16).
 11. A motor saw according toclaim 8, characterized in that the first fixing means (28) comprises asnap-in head and a corresponding seat for receiving said snap-in headfor removable attachment to said carbureter (16).
 12. A motor sawaccording to claim 2, characterized in that the seat is a resilientbushing (21) made of rubber.
 13. A motor saw according to claim 8,characterized in that the second fixing means (29) comprises a T-shapedand can be pushed-in into a corresponding T-shaped receiving groove orrecess on the casing (102).
 14. A motor saw according to claim 8,characterized in that the second fixing means (28) comprises a snap-inhead and a corresponding seat for receiving said snap-in head forremovable attachment to said casing (102).